The only powder I could find for my 38 special loads was Hi-Skor 700x, which has somewhat large flakes. Most powder measures seem to struggle to drop it accurately in small quantities. My Lee Pro Auto Disk would drop charges between 0.5gr (!) and 2.8gr. I still managed to load a few hundred rounds by shaking the measure vigorously with my hand before each drop, then carefully inspecting each case before loading a bullet and redoing the drop if it seemed off. I was able to consistently drop 2.7 or 2.8gr that way. But it was slow and tedious.

I read somewhere that strapping a vibrator to the measure would solve the problem. I ordered one from China, for $2.50, shipping included. I finally strapped it on today and boy, I'm a happy man! It consistently drops 2.8gr now. Every single time. Without doing anything special.